How many stereoisomers (configurational isomers, optical and geometrical together, counting a meso form once) does the constitution shown have?

The compound is 2,3-dichlorobutane, with two stereocentres (C2, C3) bearing identical substituent sets. The $2^2=4$ labelled combinations collapse because (2R,3S) and (2S,3R) are the same meso compound, leaving (2R,3R), (2S,3S) and meso: 3 stereoisomers (confirmed with RDKit).